In the present paper we study chemical potential of a generalized Hubbard model with correlated hopping at half-filling using a generalized mean-field approximation. For the special case of the model the approach reproduces the exact results: metal-insulator transition, ground state energy. Chemical potential of generelized Hubbard model with correlated hoppig as function of hopping integrals at zero temperature is found. It is shown that chemical potential of the model is temperature-dependent. The dependences of chemical potential of a generalized Hubbard model with correlated hopping on the model parameters are different in metallic and insulating phases leading to a kink at the point of metal-insulator transition in the ground state. With the increase of temperature the kink in the chemical potential curve disappears. The obtained results differ from those of the Hubbard model indicating the important role of correlated hopping.
Motivated by recent experimental studies that have found signatures of a correlated insulator phase and tuning superconductivity in twisted bilayer graphene, we study the temperature-dependent conductivity, the spin correlation and the superconducting pairing correlation within a two-orbital Hubbard model on an emergent honeycomb lattice. Evaluation of the temperature dependence of the conductivity demonstrates that there is a metal-insulator transition, and the Mott phase at strong coupling is accompanied by antiferromagnetic order. The electronic correlation drives a
d+id superconducting pairing to be dominant over a wide filling region. All of the dc conductivity, the spin correlation and the superconductivity are suppressed as the interlayer coupling strength increases, and the critical
Uc for metal-insulator transition is also reduced. Our intensive numerical results reveal that the TBG should be a uniquely tunable platform for exploring correlated states.